The present invention relates to electrical circuitry, and more particularly, but not exclusively, relates to circuitry to regulate electrical power output by an alternator.
It is sometimes desired to sense current flow through selected conductive pathways of electricity generating devices. Of particular interest is the detection of electric current through the field coil of a vehicle alternator. Typically, during operation of an alternator, excitation current is supplied to the field coil through an electronically controlled driver. One proposed scheme for detecting field winding current is based on a special Field Effect Transistor (FET) driver with a dedicated current sense output. This output provides a signal proportional to the excitation current flowing through the special driver to the field coil. Unfortunately, such special drivers are often relatively expensive.
Another proposed scheme has been to detect current flowing to the field coil with a resistor placed in the excitation current pathway between the driver and the field coil, and/or in the excitation current pathway between the driver and a power supply rail. One drawback to this scheme is that excessive power loss can result unless the resistor has a relatively low resistance value. Such low resistance values can severely limit current detection accuracy. Moreover, because these schemes only measure excitation current levels, it is often difficult to determine the actual peak current flowing through the field coil.
Thus, a need remains for further advancements in this area of technology. The present invention meets this need.
One embodiment of the present invention includes unique electrical circuitry. Other embodiments include unique integrated circuits, apparatus, and methods for regulating an electrical power generating device.
A further embodiment of the present invention includes an electrical generator and a recirculation circuit electrically coupled to a component of the generator. The recirculation circuit includes a current sensing device electrically coupled in series with a unidirectional current device. In one form, the electrical generator component is a field coil of an alternator, the current sensing device is a sense resistor, and the unidirectional current device is a diode.
Yet a further embodiment of the present invention includes an alternator with a field coil and circuitry including a switching device, a current sensing device, and a unidirectional current device. The unidirectional current device is coupled in series with the current sensing device and is operable to route more electric current through the current sensing device during one state of the switching device than during a different state of the switching device.
Still a further embodiment of the present invention includes: providing circuitry comprising a switching device, a current sensing device, and a unidirectional device; controlling electrical current flow through an alternator field coil with the circuitry; and routing more electric current through the unidirectional current device and the current sensing device from the alternator field coil during one state of the switching device than during a different state of the switching device. In one form, the unidirectional current device includes a diode, the current sensing device includes a resistor, and the switching device includes a transistor. For this form, the one state corresponds to a nonconductive condition of the transistor and the different state corresponds to a conductive condition of the transistor. In this form, an integrated circuit is also included that can selectively activate the transistor to modulate excitation current supplied to the field coil, and includes a pair of differential inputs coupled across the resistor to generate a signal corresponding to current flow through the alternator field coil.
Another embodiment of the present invention comprises: establishing a first state of a driver to direct electric current flow through an alternator field coil along a first path; changing the driver from the first state to a second state to route electrical current flowing through the alternator field coil along a second path different than the first path; and sensing different nonzero levels of an electrical current with a current sensing device in the second path that is not included in the first path. A peak current through the alternator field coil can be determined through such sensing.
As used herein, xe2x80x9ctransistor devicexe2x80x9d broadly refers not only to a single transistor, but also to a transistor and one or more other electronic elements arranged to provide an active device that includes at least three terminals. By way of nonlimiting example, a transistor device includes multiple transistor combinations, such as two or more transistors coupled in parallel, the Darlington configuration, the Sziklai configuration, or such different multiple transistor configurations as would occur to those skilled in the art.
As used herein, xe2x80x9ctransistorxe2x80x9d broadly refers to any transistor type, including, but not limited to, a Bipolar Junction Transistor (BJT) or Field Effect Transistor (FET); where FET types include the Junction Field Effect Transistor (JFET) variety or Insulated Gate Field Effect Transistor (IGFET) variety to name a few (it being understood that IGFETs encompass, but are not limited, any type of Metal Oxide Semiconductor Field Effect Transistor (MOSFET)).
One object of the present invention is to provide unique circuitry for an electrical power generation device.
Another object of the present invention is to provide a unique integrated circuit, apparatus, or method for regulating an electrical power generation device.